Selective activation of peroxymonosulfate to singlet oxygen by engineering oxygen vacancy defects in Ti3CNTx MXene for effective removal of micropollutants in water

Defect engineering is an effective strategy to boost the catalytic activity of MXene towards heterogeneous peroxymonosulfate (PMS) activation for water decontamination. Herein, we developed a facile approach to fine-tune the generation of oxygen vacancies (OVs) on Ti3CNTx crystals by Ce-doping (Ce-Ti3CNTx) with the aim of mediating PMS activation for the degradation of micropollutants in water. By varying the dopant content, the OV concentrations of Ti3CNTx could be varied to enable the activation of PMS to almost 100% singlet oxygen ( 1 O 2 ), and hence the effective degradation of sulfamethoxazole (SMX, a model micropollutant). Various advanced characterization techniques were employed to obtain detailed information on the microstructure, morphology, and defect states of the catalysts. The experimental results showed that SMX removal was proportional to the OVs level. Density functional theory (DFT) models demonstrated that, in contrast to pristine Ti3CNTx, the OVs on 10%CeTi3CNTx could adsorb the terminal O of PMS, which facilitated the formation of SO5 center dot - as well as the generation of 1 O 2 . We further loaded the optimized catalysts onto a polytetrafluoroethylene microfiltration membrane and also demonstrated the efficient removal of SMX from water using a convection-enhanced mass transport flow through configuration. This study provides new insights into the effective removal of micropollutants from water by integrating state-of-the-art defect engineering, advanced oxidation, and microfiltration techniques.

Automated summary

Defect engineering through Ce doping was used to tune the oxygen vacancy concentration on Ti3CNTx crystals, enabling efficient degradation of micropollutants in water. The results showed that the oxygen vacancy level was proportional to the removal of sulfamethoxazole (SMX). Loading the optimized catalysts onto a microfiltration membrane demonstrated efficient removal of SMX from water. This study provides new insights into the effective removal of micropollutants from water by integrating defect engineering, advanced oxidation, and microfiltration techniques.